Mold for lenses



Oct. 9, 1934. J, KOUBEK A 1,976,350

MOLD FOR LENSES Filed March l0, 1952 Patented Oct. 9, 1934 i UNITED STATES MOLD FOR LENSES John L. Koubek, Ande rson, 1nd., assigner, y by mesne assignments, to General Motors Corporation, Detroit,

2. Claims.

' In the prior patent of C A. Michel, No. 1,884,076, granted October 25, 1932, there is disclosed animproved type of automobile headlamp in which the -lens is held to the lamp housing by a contractible liens ring. If 'all the advantages of this design are 'to be obtained it is unavoidable that the gasket between the lens and reflector will be exposed to View, and in that application there are disclosed several methods of concealing the gasket thereby greatly improving the appearance of the lamp.

In the present application there is disclosed a better means for concealing the gasket. The margin of `the lens that overlies the gasket is 15A provided with conical protuberances, preferably on the side toward the gasket. After a great deal of experimental work I have found that the best type of cone to be used is one having an e angle between 80 and 90. With either a lesser i angle or a greater angle, the glass is partly transparent, impairing the appearance of the lamp. When the specified angles are employed, most of the light striking the outside of the margin of the lens is reected either at its outer or its inner g surface, so that the gasket is effectually concealed.

The reflected light also gives an ornamental appearance to the lamp. The same sparkling effect will also be obtained when light from the head- ,Y lamps of an approaching car, or any other source l:so of illumination, strikes the lens at night, but the effect will be very slight because of the almost equal brilliancy of the rays returned from the reector of the headlamp. A The discovery that cones falling Within the 35 range of from 80 to 90 adequately conceal the gasket came about partly as a result of an effort to lengthen the life of the mold used to shape the lens. I found that if the mold was provided with conical depressions of 90 angle, after shaping relatively few lenses, for example, around 200, the walls and edges of the depressions burned away to such an extent that the conical protuberances thereafter formed exceeded 90, rendering the glass transparent and exposing the gasket. v After considerable experimenting I found that by originally making the depressions in the mold considerablyless than 90, a great many more lenses could be made from the same mold before the cones were so enlarged as to exceed 90 and 5o render the glass transparent. After considerable trial I found that an initial angle of about produced satisfactory non-transparent glass, and gave a mold that produced non-transparent glass throughout its life, the burning away of the metal t5 during the life of the mold never resulting in pro- Mich., a corporation of Delaware Application March 10, l

932, Serial No. 597,919

tuberances of greater angle than The present invention has to do with an improved mold having cones of reduced angle insuring long life to the mold and at the same time providing a lens with an effective gasket-concealing configuration. G0

Another feature about my protuberances is their small size. This is essential Where, as in my prefel-red design, they bear directly against the gasket, and form one of the sealing surfaces. A multiplicity of small projections likewisedoesa 5r better job of concealingthe gasket than a few large projections.

Figure 1 is a front View of a headlamp embodying my invention.

Figure 2 is a section on line 2--2 of Figure 1.

Figure 3 is an enlarged section through the margin of the lens, shown in Figures 1 and 2.

Figure 4 is a similar view of the modification.

Figure 5 is a plan view of a portion of the plunger used to form the cones on the margin of 75 the lens.

Figure 6 is a section on line 6--6 of Figure 5.

Fig. 7 is a fragmentary section through the edge portion of the cooperating mold parts in the act of shaping the lens.

The headlamp comprises, as usual, the housing 10 in which is located reector 12 equipped with the usual incandescent bulb. Lens 14 is secured to the housing by split lens ring 16, which may be contracted about the housing by rotating clamping screw 18. This action locks the lens ring in the groove 20 in the lamp housing, and draws the lens toward the reflector by the camming action of the forward portion of the lens ring on the cam shoulder 21, formed on the periphery of the lens. A gasket 22 is mounted in a groove in the reflector, and engages the rear face of the margin of the lens, sealing the lens and reector against entrance of dust. As in the prior Michel e application, referred to above, the gasket 22 would be visible from the front of the lamp were it not for the special treatment I have applied to the margin of the lens. This treatment consists in forming on the inner face of the lens a series 0f contiguous conical protuberances 24. The pro- 100 tuberances are made small, usually not over lg in diameter, so that they will make good sealing contact with the gasket 22. Their small size also assists in rendering that portion of the lens non-transparent.

In Figures 5 and 6, I have shown a portion of the mold used in making the lenses. In Fig. 7, there is shown a fragmentary section through an edge portion of the cooperating mold parts as they appear when shaping the glass. The type '110' of lens to which this invention relates is made usually in automatic machinery by simply stamping the desired conguration upon a gob of glass as indicated in Fig. 7. One part of the mold, which may be of any desired material, usually metal, is drilled to provide contiguous conical depressions 36 separated by rather sharp ridges 38. As previously explained, I have found it important that a new mold should have conical depressions with an angle of for in the subsequent use of the mold the metal burns away, particularly at the sharp edges 38, this resulting in increasing the angle as indicated by the dotted lines in Figure 6. When the angle has increased to more than I have found the resulting product to be so transparent that it no longer conceals the gasket. However, this deterioration takes place so slowly that the mold becomes useless for other reasons before the angle of the cone has become excessively enlarged. In Figure 4 I have shown a modification, where thelens is plain. This lens is provided with an annular bead 40, providing a shoulder 42, which is useful in eentering the lens in the lens ring. The bead 40 'produces prismatic action which makes it desirable to tilt the axes of the cones inwardly 9 toward the front faces of the lens. This tilting of the cones compensates for the refraction of light on the surface of the bead so that when the light rays are received in the small glass cones they will be entering approximately parallel to the axes of the cones.

Although I have experimented with many different congurations of glass for use in this relation, I believe the cones of angles between 80 and 90 are far superior not only for the reasons previously pointed out, but also because of the fact that a better seal may be obtained where conical members engage the gasket, for the conical depressions may be easily formed in the mold by drilling.

I claim:

1. A mold for use in the manufacture of lenses for lamps, having a marginal portion adapted to shape a marginal portion of the lens which is exposed to view when the lens is mounted in the lamp, said marginal portion of the mold being covered with conical cavities having included angles of substantially less than 90 but more than 80 to form correspondingly shaped protuberances in the said marginal portion of the lens to render said portion non-transparent.

2. In apparatus for the manufacture of lenses for lamps the combination of a mold having a marginal portion adapted to shape a marginal portion o1 the lens which is exposed to view when the lens is mounted in the lamp, said marginal portion of the mold being covered with contiguous conical cavities having included angles of substantially less than 90 but more than 80 to iorm correspondingly shaped protuberances in the said marginal portion of the lens to render said portion non-transparent, and a cooperating mold having a portion provided With a face taopposite said marginal portion of the rst mold.

JOHN L. KOUBEK. 

